BACKGROUND: Access to syphilis testing and treatment is frequently limited for men who have sex with men (MSM). A two-armed randomised controlled trial compared feasibility and costs of facility-based syphilis testing with self-testing among MSM in Zimbabwe. METHODS: This randomised controlled trial was conducted in Harare, with participants randomised 1:1. Syphilis self-testing was offered in community-based settings. The primary outcome was the relative proportion of individuals taking up testing. Total incremental economic provider and user costs, and cost per client tested, diagnosed and treated were assessed using ingredients-based costing in 2020US$. RESULTS: A total of 100 men were enrolled. The two groups were similar in demographics. The mean age was 26years. Overall, 58% (29/50) and 74% (37/50) of facility- and self-testing arm participants, respectively, completed syphilis testing. A total of 28% of facility arm participants had a reactive test, with 50% of them returning for confirmatory testing yielding 28% reactivity. In the self-testing arm, 67% returned for confirmatory testing, with a reactivity of 16%. Total provider costs were US$859 and US$736, and cost per test US$30 and US$15 for respective arms. Cost per reactive test was US$107 and US$123, and per client treated US$215 and US$184, respectively. The syphilis test kit was the largest cost component. Total user cost per client per visit was US$9. CONCLUSION: Syphilis self-testing may increase test uptake among MSM in Zimbabwe. However, some barriers limit uptake including lack of self-testing and poor service access. Bringing syphilis testing services to communities, simplifying service delivery and increasing self-testing access through community-based organisations are useful strategies to promote health-seeking behaviours among MSM.